The present invention relates to an ion source, and more particularly to an ion source operable in a wide operating voltage range and a method of drawing out an ion beam from the ion source.
In recent years, attention has been paid to the formation of a film using the ion beam mixing method and the ion beam assisted method, and various processes for forming a thin film by combining these methods have been developed. Generally speaking, for the ion beam mixing method, it is required to operate an ion source on a voltage of tens of kilo-volts, while, for the ion beam assisted method, it is required to operate an ion source on a voltage of hundreds to thousands of volts. However, the operation voltage of a conventional ion source is restricted within a narrow range. Accordingly, a conventional thin-film depositing (or forming) apparatus includes an ion source for a high voltage operation and another ion source for a low voltage operation, as described in, for example, JP-A-No. 61-133,376. For the technology with respect to an ion source, reference may be made to U.S. Pat. No. 4,713,585 to Y. Ohno et al., U.S. Pat. No. 4,739,169 to Y. Kurokawa et al., and U.S. patent application Ser. No. 942,711 by T. Sato et al. filed in the name of the same assignee and already allowed.